The present invention relates to putter type golf club heads and in particular to an improved ball striking face groove configuration for use with putters.
Golf balls are made with a variety of dimple patterns in order to improve the aerodynamic flight characteristics of the ball that has been struck by a golf club with a full golf swing. The dimples create an aerodynamic surface thereby allowing the ball to achieve lift and thus travel longer and with more accuracy than if the balls were made with a smooth surface. The irregular surface created by the dimples has little effect on full swing shots because of the compression of the golf ball. Little consideration has been given to the way a golf ball reacts when the ball is hit softly, as when stuck by a putter. However these shots that are hit softly with little compression are subject to what is known in the industry as the “dimple effect”. Briefly described, the dimple effect is the tendency of a golf ball to start off the intended target line when the ball is struck by the putter face at the edge of a dimple. The inward concave shape of a dimple acts as a flat surface running from one edge of the dimple to the other. As the flat, hard ball striking surface of a putter comes in contact with the edge of a dimple, the other side of the dimple will cause the ball to slightly rotate as the dimple tries to square itself with the flat putter surface. This starts the ball slightly off line. This inaccuracy is magnified as the length of the putt increases. The larger the dimples, the more pronounced the error tends to be with all other parameters of the stroke being equal. While grooved putter faces have improved the quality of roll by reducing skid, the dimple effect is still present and effects accuracy as described above.
The advantages of the grooves on the ball striking face of a putter outweigh the disadvantages of the dimple effect. Typically golf putters incorporate a smooth, flat non-grooved ball striking face. Flat face putters provide a maximum face surface to present to the irregular surface of the golf ball. Most of these putters have four to six degrees of loft, it being common wisdom this amount of loft is necessary to cleanly launch a golf ball on top of the irregular surface of a putting green. Sometimes it is no more than the weight of the ball that causes a slight depression in the green's surface directly under the ball as the golfer walks from the place where the shot to the green was hit to the location on the green where the ball is at rest. This lofted design causes the golf ball to be launched slightly above the green's surface with a slight back spin. In turn, the golf ball initially skips and skids before fully engaging the green surface and beginning to roll. This further led to the development of putters with closely spaced grooves on the ball striking face that created lift without loft to get the golf ball out of its depression and rolling almost immediately with little or no skid.
Examples of these grooved face putters include Applicant's own patents, U.S. Pat. No. 5,168,239 titled Groove Configuration for a Golf Club and U.S. Pat. No. 5,709,616 titled Groove Configuration for a Putter Type Golf Club Head. Both the patents teach the use of closely spaced, straight, horizontal grooves each with a slightly different groove configuration. U.S. Pat. No. 5,168,239 teaches the use of asymmetrical saw-toothed shaped grooves. U.S. Pat. No. 5,709,616 teaches the use of symmetrical grooves wherein the land areas between the grooves is smaller than the groove spacing.
Both of these groove technologies grip and lift a golf ball at impact by the putter face. However, because this groove configuration is straight in a heel to toe, or horizontal direction when the putter is properly soled relative to the green's surface, impacts on the edge of a dimple cause the ball to start slightly off line.
Other attempts at providing a ball striking face configuration for more accurate golf ball roll is shown in U.S. Pat. No. 5,637,044 to Swash that uses a plurality of equally spaced concentric, arcuate grooves surrounding the center of the ball striking face of the putter. The arcuate configuration promotes the possibility of the ball going further off line when the ball is struck off center on a downward portion of the arcuate groove pattern or when a golfer swings the putter head in a diagonal stroke path.
The patent to Reach U.S. Pat. No. 1,337,958 teaches the use of grooves on a wedge type golf club wherein the grooves are configured in a set of curves diagonally across the face from the lower toe to the upper heel. The grooves are formed in a single wave pattern, having a single upward and a single downward configuration. In the preferred embodiment the grooves are substantially wider than conventional grooves with the groove spacing being approximately the same size as the land area. As is customary when using a wedge, the face can be laid open to create greater amounts of loft in order to hit the ball higher in the air. When the club face is used in a laid open position, the ball travels from the lower heel to the upper toe in diagonal direction across the face of the wedge. Unlike conventional wedges with straight horizontal grooves that can only grip the ball at a diagonal when the face is laid open, producing less backspin, the Reach curved singular wave groove pattern is designed to be perpendicular to the path of the ball regardless of how much the golfer lays the face open, producing both higher ball flight and more backspin.
Other putter face configurations to control the golf ball struck by the putter include the use of dimples and raised protuberances on the face of the putter. In addition a wide variety of lines, geometrical designs and decorative patterns on the face of a putter have been used in an attempt to improve the contact between the putter face and the golf ball at impact during the execution of a putting stroke. For example, U.S. Pat. No. 6,257,994 to Antonious discloses a variety of grooved lines as well as geometrical patterns on the face of a putter.